Operation Transformation is over for another year – or, in my case, my first year – and it's certainly been a rollercoaster. I didn't know what to expect when I signed up, having never done anything quite like this before, and I suppose I thought that, as a GP with an interest in obesity and lifestyle medicine, it would be relevant and challenging.

What I didn't really expect was the huge bond of affection and respect I developed for all six leaders – who put themselves forward and took on what amounts to an eight-week endurance test, both in terms of diet and exercise, but also in terms of the pressure they're under with cameras and the nation following their every move.

The other thing I didn't really foresee was just how much their lives were affected and hampered by their weight. The global effect on all of them can't be overstated. It consumed them. It was the reason they avoided social situations. It was the reason they wouldn't put themselves forward for things. It was the reason they felt worthless, invisible and depressed. And if their weight was the cause of all those things, it was also the effect. Obesity creates a chicken-and-egg situation where it causes you to feel incredibly negative about yourself, but that negativity is one of the things that drives you to overeat and become obese.

Breaking that cycle is hard, extremely hard. But it can be done. This year was the first year that Operation Transformation had a four 'man' multidisciplinary team of experts to support and motivate them and it worked really well. Doctor, dietician, psychologist and physical trainer – we all played a role in tackling the issues that had led to the leaders becoming obese, and in formulating a plan for moving them forward along the road to a healthier life, physically and emotionally. An incredibly skilled production team coupled with the genuinely kind and decent Kathryn Thomas also offered a deep well of support and a listening ear for all of them.

And it worked! It was never only about lbs on the scales. Every single one of them changed their habits, but far more importantly changed how they saw themselves. They worked their butts off – literally. All of them have said it was a hugely positive and life-changing experience and one they will never forget. It gave them the tools to use in the future to cope without comfort eating. It taught them about portion sizes and healthy foods. It showed just what their bodies are physically capable of and how their health and well-being is improved by a healthy lifestyle.

And despite it being tough – particularly in the beginning as they adjusted to the new regime and 'Plan A' – there were so many wonderful moments along the way. The brutal honesty of Paudie, who reconnected with his family and his community after years of withdrawal. The often hilarious but wonderfully endearing Deirdre and her husband John. Vivacious Siobhan who reordered her life and got her sparkle back. Old-for-her-years Sarah who rediscovered that she is only 24 and it's OK for her to be happy. Marc, who has struggled so much in the past but is taking pride in his present. And the Incredible Jennifer Bonus who is so strong and reduced the experts on the panel to tears – another OT first – but who is slowly allowing herself to move on after becoming a widow two years ago.

It has been an enormous pleasure and privilege to work with all of them.

I wish them well and sincerely hope that they take these eight weeks and use it as a starting point for the rest of their lives. Their transformation is only beginning.

They've inspired me and the whole country. Well done guys, you should be very proud.